This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of π–π interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graph...

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Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications

Atomically precise pieces of matter of nanometer dimensions composed of noble metals are new categories of materials with many unusual properties. Over 100 molecules of this kind with formulas such as Au25(SR)18, Au38(SR)24, and Au102(SR)44 as well as Ag25(SR)18, Ag29(S2R)12, and Ag44(SR)30 (often with a few counterions to compensate charges) are known now. They can be made reproducibly with robust synthetic protocols, resulting in colored solutions, yielding powders or diffractable crystals. They are distinctly different from nanoparticles in their spectroscopic properties such as optical absorption and emission, showing well-defined features, just like molecules. They show isotopically resolved molecular ion peaks in mass spectra and provide diverse information when examined through multiple instrumental methods. Most important of these properties is luminescence, often in the visible–near-infrared window, useful in biological applications. Luminescence in the visible region, especially by clusters prot...

Atomically Precise Clusters of Noble Metals: Emerging Link between Atoms and Nanoparticles

Nanotechnology has witnessed tremendous advancement over the last several decades. Zinc oxide (ZnO), which can exhibit a wide variety of nanostructures, possesses unique semiconducting, optical, and piezoelectric properties hence has been investigated for a wide variety of applications. The most important features of ZnO nanomaterials are low toxicity and biodegradability. Zn(2+) is an indispensable trace element for adults (~10 mg of Zn(2+) per day is recommended) and it is involved in various aspects of metabolism. Chemically, the surface of ZnO is rich in -OH groups, which can be readily functionalized by various surface decorating molecules. In this review article, we summarized the current status of the use of ZnO nanomaterials for biomedical applications, such as biomedical imaging (which includes fluorescence, magnetic resonance, positron emission tomography, as well as dual-modality imaging), drug delivery, gene delivery, and biosensing of a wide array of molecules of interest. Research in biomedical applications of ZnO nanomaterials will continue to flourish over the next decade, and much research effort will be needed to develop biocompatible/biodegradable ZnO nanoplatforms for potential clinical translation.

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Biomedical Applications of Zinc Oxide Nanomaterials

A facile Au nanoplates and reduced graphene oxide (RGO) modified glassy carbon electrode (GCE) was fabricated via a simple electrochemical method, denoted as Au/RGO/GCE. The Au/RGO/GCE electrode was used for the simultaneous detection of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The modified electrodes fabricated by different methods presented different morphologies and performances for determination of AA, DA, and UA. Three well-defined voltammetric peaks along with remarkable increasing electrooxidation currents were obtained on the Au/RGO/GCE with needle-like Au nanoplates in differential pulse voltammetry (DPV) measurements. It was found that there are linear relationships between the peak currents and the concentrations in the range of 2.4 × 10 −4 to 1.5 × 10 −3  M (AA), 6.8 × 10 −6 to 4.1 × 10 −5  M (DA), and 8.8 × 10 −6 to 5.3 × 10 −5  M (UA), and the limits of simultaneous determination (based on S/N  =  3) are 5.1 × 10 −5  M, 1.4 × 10 −6  M, and 1.8 × 10 −6  M for AA, DA and UA, respectively. Additionally, the Au/RGO/GCE electrode presented well anti-interference ability, stability and reproducibility.

A facile electrochemical sensor based on reduced graphene oxide and Au nanoplates modified glassy carbon electrode for simultaneous detection of ascorbic acid, dopamine and uric acid

Nanocarbons with different dimensions (e.g., 0D fullerenes and carbon nanodots, 1D carbon nanotubes and graphene nanoribbons, 2D graphene and graphene oxides, and 3D nanodiamonds) have attracted enormous interest for applications ranging from electronics, optoelectronics, and photovoltaics to sensing, bioimaging, and therapeutics due to their unique physical and chemical properties. Among them, nanocarbon-based theranostics (i.e., therapeutics and diagnostics) is one of the most intensively studied applications, as these nanocarbon materials serve as excellent biosensors, versatile drug/gene carriers for specific targeting in vivo, effective photothermal nanoagents for cancer therapy, and promising fluorescent nanolabels for cell and tissue imaging. This review provides a systematic overview of the latest theranostic applications of nanocarbon materials with a comprehensive comparison of the characteristics of different nanocarbon materials and their influences on theranostic applications. We first introduce the different carbon allotropes that can be used for theranostic applications with their respective preparation and surface functionalization approaches as well as their physical and chemical properties. Theranostic applications are described separately for both in vitro and in vivo systems by highlighting the protocols and the studied biosystems, followed by the toxicity and biodegradability implications. Finally, this review outlines the design considerations for nanocarbon materials as the key unifying themes that will serve as a foundational first principle for researchers to study, investigate, and generate effective, biocompatible, and nontoxic nanocarbon materials-based models for cancer theranostics applications. Finally, we summarize the review with an outlook on the challenges and novel theranostic protocols using nanocarbon materials for hard-to-treat cancers and other diseases. This review intends to present a comprehensive guideline for researchers in nanotechnology and biomedicine on the selection strategy of nanocarbon materials according to their specific requirements.

Nanocarbons for Biology and Medicine: Sensing, Imaging, and Drug Delivery

Study on the application of reduced graphene oxide and multiwall carbon nanotubes hybrid materials for simultaneous determination of catechol, hydroquinone, p-cresol and nitrite.

An eletrochemiluminescence (ECL) sensor based on ECL of peroxydisulfate solution for detecting the dopamine (DA) was proposed using reduced graphene oxide/multiwall carbon nanotubes/gold nanoparticles (rGO/MWCNTs/AuNPs) hybrid modified glassy carbon electrode (GCE). The rGO/MWCNTs/AuNPs was synthesized by an effective and facile in situ chemical reaction using polyethyleneimine (PEI) as a reducing agent for both GO/MWCNTs and AuCl 4 − . The ECL behaviors of peroxydisulfate solution have been investigated at the rGO/MWCNTs/AuNPs/GCE, and DA was found to be able to enhance the ECL of peroxydisulfate solution. Under the optimized conditions, the enhanced ECL signal intensity of peroxydisulfate solution was linear with the concentration of DA in the range between 0.20 and 70 μM ( R  = 0.9902) with a detection limit ( S / N  = 3) of 0.067 μM. Furthermore, the developed sensor exhibited a high sensitivity, good reproducibility, stability for the detection of DA. The applicability of the proposed sensor was also evaluated by detecting DA in dopamine hydrochloride injection, human urine and serum.

Dehua Yuan

Papers

Study on the application of reduced graphene oxide and multiwall carbon nanotubes hybrid materials for simultaneous determination of catechol, hydroquinone, p-cresol and nitrite.

An ECL sensor for dopamine using reduced graphene oxide/multiwall carbon nanotubes/gold nanoparticles

Facile synthesis of graphene hybrid tube-like structure for simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan.

Highly-sensitive cholesterol biosensor based on platinum-gold hybrid functionalized ZnO nanorods.

An electrogenerated chemiluminescence sensor based on gold nanoparticles@C60 hybrid for the determination of phenolic compounds